Jerry was born with a round face,flattened skull,short limbs,and retardation of motor and mental abilities.The doctors told Jerry's parents that this is because he has an extra copy of chromosome 21.Which of the following chromosomal abnormalities does Jerry have?
A)phenylketonuria
B)Turner syndrome
C)sickle-cell anemia
D)Down syndrome

Question

Quizplus · Accepted Answer

Jerry has Down syndrome, which is caused by the presence of an extra copy of chromosome 21. Phenylketonuria is caused by a mutation in a single gene, Turner syndrome involves a missing or partially missing X chromosome, and sickle-cell anemia is caused by a mutation in the beta-globin gene on chromosome 11. None of these conditions are associated with the characteristic features described for Jerry.

Jerry Was Born with a Round Face,flattened Skull,short Limbs,and Retardation